[R-390] R-390 Questions - Comments

[Dan Merz]

Mike,  I put a small fan on the left side of mine near the regulator tubes,
to get rid of some of the heat,  mounted on a plate externally so easily
removed and with no permanent mod to receiver.  This was ala design of Roy
Morgan.  Like you,  I used a small external transformer to match speaker to
the 600 ohm output impedance.  I use 12BW4's in place of 26Z5 rectifiers
(slight mod required),and I used 12BH7 in place of the ballast tube ( 1
innocuous jumper required).  These last two tube subs were done because I
didn't have the original tubes and couldn't find them at reasonable price.
The other addition I made was an outboard product detector,  easily removed
with no receiver mod and the set can be operated per original setup with
single switch on the outboard unit.  This makes for better ssb agc
performance,  but is a refinement that satisfied my curiousity about such
things.  I almost always use it however because it does improve
intelligibility somewhat on ssb.  I too could not resist having the 390 when
I encountered the set at a hamfest about a year ago at a reasonable price,
even though I already had a nice 390a that I'd put a 390 i.f. into,  happy
listening,  Dan.
-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Michael Melland
Sent: Wednesday, March 01, 2006 7:39 AM
To: r-390 at mailma n.qth.net
Subject: [R-390] R-390 Questions - Comments

Well my beloved Motorola R-390A station now has a mate.  I traded an
amplifier I had for a nice Motorola R-390 from the 1951 contract.  The tag
indicates it was a "Motorola Made For Collins Radio" and the s/n is 4449.

It works fine as it is but I'll have some cosmetic work that needs doing and
an alignment to fully restore it.  The previous owner said the audio was a
bit low but I have it hooked through a Hammond audio
600/8 transformer and it sounds fine to me.... wonder if he hooked it direct
to an 8 ohm speaker and had low audio due to that...

It is sans a number of tube shields and the top and bottom covers.  Does the
R-390 use the same top and bottom covers as the R-390A ?  Who sells R-390
covers if not... the tube shield cans I can find.  Also...
any source for the tube pullers or tools ?  The pin straighteners are
present. And, the proper power cord is provided... 3 wire ?

The only damage to speak of is a "dent" in the right rear corner that bent
the square bracket like piece on the corner.... the side panel is only
slightly bent and I can repair that... the square piece on the rear appears
to be replacable... anyone have a spare ?

I had my choice of another R-390A or this R-390 and wanted one of each ...
I'm glad I chose the R-390. 
While it sure is "similar" to my R-390A and the lineage is unmistakable...
it's really quite different.

Any suggestions or restoration tips are appreciated

Mike, W9WIS



--

Michael Melland, W9WIS
Redgranite, WI USA
"Non Sibi Sed Patriae"
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